add guide on how to download music from youtube

content/blog/how-to-download-music-from-youtube.md

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++++
+template = 'custom/blog-post.html'
+
+title = 'how to download music from youtube + thumbnail'
+description = 'a short small guide on how to download music from youtube, preserving thumbnail'
+date = '2024-08-22'
+slug = 'download-music-from-yt'
+year = 2024
+month = 8
+day = 22
+lang = 'en'
+
+[extra]
+author = 'b1ek <me@blek.codes>'
+
++++
+
+# let's get to the point.
+you need to have `yt-dlp` and `ffmpeg` installed, `magick` and `lame` for setting the mp3 cover.
+
+`yt-dlp` has the `-x` option, which automatically extracts the audio with ffmpeg. to specify the file format, use `--audio-format` (mp3, aac, etc):
+
+```
+yt-dlp https://youtu.be/oLnq2SdZvQs -x --audio-format mp3 -o flying_north.mp3
+```
+
+as you can see, the thumbnail is not preserved by `yt-dlp`:
+
+<img src='/blog-image/yt-music-no-thumb.png' />
+
+to get the thumbnail, do:
+
+```
+curl https://i.ytimg.com/vi_webp/$VIDEO_ID/maxresdefault.webp -o file.webp
+```
+
+to convert it to JPEG + crop it to 1:1 aspect ratio:
+
+```
+magick convert -crop 1:1 -gravity center file.{webp,jpeg}
+```
+
+and the last thing, to embed it inside the `.mp3`:
+
+```
+lame --ti file.jpeg flying_north.mp3
+mv flying_north.mp3.mp3 flying_north.mp3 # there's a good chance `lame` will export the file to `FILENAME.mp3.mp3`
+```
+
+so, basically it could be collapsed down to a bash script:
+
+```bash
+#!/usr/bin/env bash
+
+VIDEO_ID=oLnq2SdZvQs
+filename=file.mp3
+cover=$(mktemp)
+
+yt-dlp https://youtu.be/$VIDEO_ID -x --audio-format mp3 -o $filename
+curl https://i.ytimg.com/vi_webp/$VIDEO_ID/maxresdefault.webp -o $cover
+lame --ti $cover $filename
+```
+
+and, yay! it works
+
+<img src='/blog-image/yt-music-works-in-amberol.png' />
+